1. Technical Field
The present invention relates generally to the area of delivering multimedia services over the Internet, and more particularly to techniques for distributing live programs (e.g., video or audio) to subscribers using a data network, where client machines associated with the subscribers are configured to provide needed bandwidths to deliver the live programs with a minimum delay.
2. Description of the Related Art
Live programs, such as Oscar award evening, are traditionally broadcast over the air, in cable or via satellite. Since the Internet has been introduced as an alternative type of medium to reach the audience, efforts to broadcast live programs have led to many paradigms surrounding the well-known client-server architecture. In the server-client architecture, a server starts to feed a stream of a live program to a client upon receiving an order therefrom. Although the server-client architecture is relatively easy to implement and deployed, it was soon proved to be inefficient and incapable of supporting a large number of requests. When a live program becomes highly demanding, a server or a cluster of servers start to experience the bandwidth pressures when more and more clients request the same program at the same time.
One of the proposals to avoid the bandwidth pressures is to use distributed networks, namely each of participating client machines becoming potentially a server to provide feeding data to an ordering machine. An example is BitTorrent which is a peer-to-peer file sharing (P2P) communications protocol. BitTorrent is a method of distributing large amounts of data widely without involving an original distributor. Instead, when data is distributed using the BitTorrent protocol, recipients each supply data to newer recipients, reducing the cost and burden on any given individual source, providing redundancy against system problems, and reducing dependence upon the original distributor. However, BitTorrent does not support an “instant” playback of an ordered program. Often a user has to wait for an unpredictable amount of time before data from different places is received and assembled for playback. So BitTorrent, as of the current status, could hardly support a live broadcasting program.
U.S. Pat. No. 7,191,215 discloses unique techniques of providing media services among clients with a central server as a manager or regulator. FIG. 1 duplicates FIG. 2A of U.S. Pat. No. 7,191,215, that shows an exemplary configuration 200 of a distributed network system. A server 202, presumably managed and/or populated by a service provider, is configured to handle the delivery of video (or multimedia) services to users via local machines or boxes 206-1, 206-2, . . . 206-n. Different from the client-server architecture in which a server is caused deliver video data to a subscriber upon receiving a request therefrom, the server 202 is not responsible for delivering the content in response to a request from a user, and instead, it is configured to provide source information as to where and how to retrieve at least some of the content from other clients (e.g., boxes). In other words, a server in the typical client-server architecture requires to have a direct access the content when servicing the clients, while the server 202 does not need necessarily to access the content to provide the content to the clients. Instead, some of the boxes 206-1, 206-2, . . . 206-n are respectively configured to supply part or all of the content to each other.
According to one embodiment, when fulfilling a request from a local machine or a box (e.g., 206-1), communication between the server 202 and the box 206-1 over the network paths 208-1 and 210 may be limited to small-scale requests and responses (e.g., of small size and very short). A server response to a request from a box may include source information (e.g., identifiers), authorization information and security information. Using the response from the server 202, the box may be activated to begin playback of a title (e.g., 207-1). Substantially at the same time, the box may initiate one or more requests to other boxes (e.g., 206-2 and 206-n) in accordance with the source identifiers to request subsequent portions of the title (e.g., 207-2 and 207-n). Assuming proper authorization, the requesting box receives the subsequent portions of the data concurrently from the other boxes. Because of box-to-box communication of content, the bandwidth requirement for box-to-server communications over the network paths 208-1 and 210 is kept low and typically short in duration.
In one aspect, U.S. Pat. No. 7,191,215 has fundamentally resolved the bandwidth issues that are experienced in the client-server architecture and made an entire video delivery system independent from the number of the users. In reality, U.S. Pat. No. 7,191,215 performs better with more users because more client machines available to supply requested data means more bandwidths for servicing others, while the client-server architecture starts to hit its limits when the number of its users exceeds a certain number.
The present invention discloses techniques for distributing a live broadcast program using a distributed network. As will be appreciated by those skilled in the art, one embodiment of the present invention may be advantageously used in a system designed in accordance with U.S. Pat. No. 7,191,215 but can also be used in general for distributing live contents over distributed networks.